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3 years ago

How has the work of chemists advanced cancer treatment?

Chemistry

2 answers:

jeyben [28]3 years ago

6 0

Answer:

Explanation:

it wouldn't be A because that makes no sense

theirs no pill or any type of drug that can slow it down but their is a treatment plan for it

(It could be c or d)

Oduvanchick [21]3 years ago

6 0

Answer:

Its B

Explanation:

A P E C

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Complete each of the definitions with the appropriate phrase. Precision means that measurements are close to Accuracy means that

sergiy2304 [10]

Answer: Precision means that measurements are close to each other . Accuracy means that measurements are close to accepted value

Explanation:

Precision refers to the closeness of two or more measurements to each other.

For Example: If we weigh a given substance five times and you get 5.0 kg each time. Then the measurement is very precise.

Accuracy refers to the closeness of a measured value to a standard or known value.

For Example: If the mass of a substance is 5.0 kg and one person weighed 4.9 kg and another person weighed 3.9 kg. Then, the weight measured by first person is more accurate.

Thus Precision means that measurements are close to each other . Accuracy means that measurements are close to accepted value.

5 0

2 years ago

Draw the product that valine forms when it reacts with excess CH3CH2OH and HCl followed by a wash with aqueous base.

-BARSIC- [3]

Answer:

Product: ethyl L-valinate

Explanation:

If we want to understand what it is the molecule produced we have to analyze the reagents. We have valine an amino acid, in this kind of compounds we have an amine group ( $NH_2$ ) and a carboxylic acid group ( $COOH$ ). Additionally, we have an alcohol ( $CH_3CH_2OH$ ) in the presence of HCl (a strong acid) in the first step, and a base ( $OH^-$ ).

When we have an acid and an alcohol in a vessel we will have an esterification reaction. In other words, an ester is produced. As the first step, the oxygen in the C=O (in the carboxylic acid group) would be protonated. In the second step, the ethanol attacks the carbon in the C=O of the carboxylic acid group producing a new bond between the oxygen in the ethanol and the carbon in the carboxylic acid. In step 3, a proton is transferred to produce a better leaving group ( $H_2O$ ). In step 4, a water molecule leaves the main structure to produce again the double bond C=O. Finally, a base ( $OH^-$ ) removes the hydrogen from the C=O bond to produce ethyl L-valinate

See figure 1

I hope it helps!

7 0

3 years ago

At equilibrium the reactant and product concentrations are constant because a change in one direction is balanced by a change in

Anna [14]

Answer: a. The concentrations of the reactants and products have reached constant values

Explanation:

The reactions which do not go on completion and in which the reactant forms product and the products goes back to the reactants simultaneously are known as equilibrium reactions. For a chemical equilibrium reaction, equilibrium state is achieved when the rate of forward reaction becomes equal to rate of the backward reaction.

Equilibrium state is the state when reactants and products are present but the concentrations does not change with time and are constant.

Equilibrium constant is defined as the ratio of concentration of products to the concentration of reactants each raised to the power their stoichiometric ratios. It is expressed as $K_{eq}$

K is the constant of a certain reaction when it is in equilibrium, while Q is the quotient of activities of products and reactants at any stage other than equilibrium of a reaction.

For a equilibrium reaction,

$A\rightleftharpoons B$